Cellular modem processing

ABSTRACT

A cellular mobile station including a modem processor and memory. The memory includes instructions for the modem processor to perform layer  1  processor operations, layer  2  processor operations, and layer  3  processor operations. The modem processor executes the instructions to perform processor operations for the cellular mobile station to communication data as per a cellular communications protocol. In one example, the mobile station includes different levels of memory to provide different deterministic access times

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to a cellular mobile station and inparticular to cellular modem processing in a cellular mobile station.

2. Description of the Related Art

Cellular mobile stations such as e.g. cellular phones and wireless PDA'stypically include modem circuitry for performing modem operations forcellular communications. These operations typically are classified bycommunications protocol layers. Examples of communication protocollayers include a physical layer, a data layer, and layers above the datalayer such as (with the Open Systems Interconnect (OSI) model) a networklayer, a transportation layer, a session layer, a presentation layer,and an application layer.

Cellular mobile stations typically perform the modem operations of thesedifferent layers with multiple processors. For example, one processormay perform modem operations of the physical layer and/or data layer andanother processor may perform modem operations of higher layers. In oneexample, a cellular mobile station uses a digital signal processor forthe physical layer operations and a microcontroller unit processor forthe higher layer operations.

What is desired is an improved cellular mobile station.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerousobjects, features, and advantages made apparent to those skilled in theart by referencing the accompanying drawings.

FIG. 1 is a block diagram of one embodiment of a cellular mobile stationaccording to the present invention.

FIG. 2 is a view of a communication protocol stack.

FIG. 3 shows one embodiment of a cellular modem instruction partitioningaccording to the present invention.

The use of the same reference symbols in different drawings indicatesidentical items unless otherwise noted.

DETAILED DESCRIPTION

The following sets forth a detailed description of a mode for carryingout the invention. The description is intended to be illustrative of theinvention and should not be taken to be limiting.

FIG. 1 is a block diagram of a cellular mobile station according to thepresent invention. Mobile station 101 may be e.g. any one of a cellularphone, wireless PDA, or wireless modem. Mobile station 101 includes anantenna 105 for transmitting and receiving wireless signals as per acellular communications protocol. Antenna 105 is coupled to RF interface107 which is coupled to analog to digital (A/D) and digital to analog(D/A) circuitry 109. In the embodiment of FIG. 1, mobile station 101includes an integrated circuit 103 having both a microcontroller unit(MCU) processor 145 and a digital signal processor (DSP) 127. In theembodiment shown, MCU processor 145 is utilized to perform applicationsof the mobile station 101 such as e.g. games, video, and word processingapplications.

DSP 127 is utilized in mobile station 101 as a cellular modem processor.DSP 127 is utilized to perform modem operations that enable station 101to communicate encoded data (e.g. voice and/or information) over acellular phone network as per a cellular communications protocol. Aswill be explained later, DSP 127 can perform processor modem operationsof layer 1 (physical layer), layer 2 (data layer), and layer 3 of acellular communication protocol (See FIG. 2).

Cellular mobile station 101 includes a control interface 113, an RF I/Qdata interface 115, and a layer 1 (L1) timer 117 coupled to DSP bus 125,circuitry 109, and RF interface 107. In the embodiment shown, integratedcircuit 103 also includes hardware accelerators 123, audio serialinterface 121, and a subscriber identification module (SIM) cardinterface 127 coupled to DSP bus 125. Mobile station 101 includes audiocircuitry 104, speaker 108, and microphone 106 for providing audio inputand output to mobile station 101. In other embodiments, at least some ofaudio circuitry 104 may be implemented in integrated circuit 103.

In the embodiment of FIG. 1, DSP 127 is operably coupled to DSP bus 125via level 1 cache 131 and bridge 133. Integrated circuit 103 alsoincludes a level 1 memory 129, a level 2 memory 135, a level 2 cache137, and an external memory interface 139. Level 1 memory 129 and level2 memory 135 may include non volatile and/or volatile memory.

In one embodiment, data is encoded by DSP 127 as per a cellularcommunications protocol and provided via bridge 133, DSP bus 125, RF I/Qdata interface 115, and circuitry 109 to RF interface 107 to betransmitted over antenna 105. Encoded data is received by DSP 127 fromantenna 105 via RF interface 107, circuitry 109, RF I/Q data interface115, bus 125, and bridge 133. Layer 1 timer 117 and control interface113 provide the requisite timing and control information for the data tobe communicated according to the cellular communications protocol.

In the embodiment of FIG. 1, integrated circuit 103 includes MCUprocessor 145. MCU processor 145 is coupled to memory 151, peripherals149, and external memory interface 139. MCU processor 145 and DSP 127are each coupled to messaging unit 147 for exchanging messages therebetween. MCU processor 145 and DSP 127 also can exchange data in sharedlevel 3 memory 141. In some embodiments, memory 141 may be located inintegrated circuit 103.

In some embodiments, integrated circuit 103 includes security featuresfor DSP 127. For example, in one embodiment, integrated circuit 103includes a hardware accelerator (e.g. 123) which generates a digitalsignature for a section of DSP 127 instructions for authentication. Inanother embodiments, integrated circuit 103 includes a hardwareaccelerator (e.g. 123) that encrypts and decrypts key variables andstores them in a volatile memory of the hardware accelerator. Thesesecurity features protect the operation of DSP 127 from maliciousinstructions which could interfere with normal modem operation.

Information to be transmitted as per cellular communications protocolmay be provided to DSP 127 from MCU processor 145 for transmission.Furthermore, information received as per a cellular communicationprotocol may be provided from DSP 127 to MCU processor 145. In oneembodiment, the information to be transmitted and the informationreceived may be exchanged between DSP 127 and MCU processor 145 by oneof the processors writing the information to a portion of shared memory141 and the other processor accessing the information from the sharedmemory. A pointer may be exchanged between processors that points to theshared memory location of the data. In one embodiment, station 101implements an interprocessor communication protocol for managing thecommunications between processor 145 and DSP 127. The use and managementof a shared memory is abstracted by the interprocessor communicationprotocol. Examples of interprocessor communication protocols may befound in U.S. patent application Ser. No. 10/610,746, entitled “AnInterprocessor Communication Protocol,” filed Jul. 1, 2003 and U.S.patent application Ser. No. 10/643,327, entitled “Method and Apparatusfor Providing Interprocessor Communications Using Shared Memory,” filedAug. 19, 2003, both of which are hereby incorporated by reference intheir entirety.

In some embodiments, other types of processors may be utilized in placeof DSP 127. Also in other embodiments, mobile station 101 may have otherconfigurations. For example, other embodiments may not include SIM card121 or hardware accelerators 123. Still in other embodiments, MCUprocessor 145 and DSP 127 may be implemented on separate integratedcircuits. Still further in other embodiments, a mobile station may onlyinclude a DSP and no MCU processor.

FIG. 2 shows a stack 205 of cellular communication protocol layers andhow they correspond to OSI reference model stack 201. Operations of acellular communication protocol layer are operations for performing thefunctions designated to the layer. Layer 1 of stack 205 corresponds tothe physical layer of the OSI model. Layer 1 operations may include(depending upon the particular cellular communications protocol)modulation operations, demodulation operations, interleaving operations,deinterleaving operations, channel encoding operations, channel decodingoperations, channel equalization operations, synchronization operations,automatic gain control operations, and automatic frequency controloperations.

Modulation operations include operations to place encoded channel datainto a carrier signal for transmission. These operations may changeeither the amplitude, frequency, or phase of a carrier signal wave in away that represents the original signals. Some examples of digitalmodulation techniques that may be implemented by station 101 include:ASK

(Amplitude Shift Keying), FSK (Frequency Shift Keying),Gaussian-filtered Minimum Shift Keying (GMSK), QPSK(Quadrature PhaseShift Keying) and QAM (Quadrature Amplitude Modulation).

Demodulation operations include operations to recover the encodedchannel data from a carrier which has been used to transmit the signalover a transmission medium. Demodulation operations may includeoperations for the coherent detection of the received signal toaccurately estimate the channel phase and attenuation to allow forseparation of the transmitted signal from the carrier.

Interleaving operations include operations utilized to scramble theorder of data symbols to be transmitted over a channel in such a waythat, when they are descrambled (at the receiver), any burst of channelerrors will be spread out in time and thus appear as random errors tothe decoder.

Deinterleaving operations include operations utilized to unscramble thesymbols that were scrambled by the interleaving operations.Deinterleaving is performed on the received symbols, prior to channeldecoding.

Channel encoding operations include operations for adding redundant datainto a transmitted bit stream before transmission, in order to protectthe bit stream from errors that may occur. An example of one encodingtechnique that may be implemented by station 101 is convolutionalencoding.

Channel decoding operations include operations for inverting the channelencoding process and for attempting to identify and correct anytransmission errors. In one embodiment, a Viterbi algorithm may be usedto decode convolutional codes.

Equalization operations include operations used to extract the desiredsignal from the unwanted reflections. Equalization operations maybe usedto find out how a known transmitted signal is modified by multi-pathfading, and constructing an inverse filter to extract the rest of thedesired signal.

Synchronization operations include operations used to bring two signalsor the wideband components of two signals into time alignment. Forexample, a Delay Locked Loop (DLL) may be used to bring two signals intocloser alignment and keep them aligned.

Automatic gain control (AGC) operations include operations used toautomatically adjust the gain in a specified manner as a function of aspecified parameter, such as received signal level.

Automatic frequency control (AFC) operations include operations utilizedto maintain the frequency of a receiver's reference oscillator withinthe specified limits with respect to a reference frequency such as thebase station transmitter.

Layer 2 corresponds to the data layer of OSI model stack 201. Examplesof layer 2 operations may include (depending upon the particularcellular communications protocol) medium access control (e.g. multipleaccess control) operations and logical link control (e.g. link accesscontrol) operations.

Medium Access Control operations include operations related to themanagement of the shared transmission resources, such as multiplexing ofthe packet data physical channels and the radio link connectionsassociated with the packet data physical channels.

Logical Link Control operations include operations associated with thesequence and validity of data packets. Logical Link Control operationsare utilized, for example, for maintaining sequence order of framesacross one or more connections; for the detection of transmission,format, and operational errors on a logical link connection; forrecovery from detected transmission, format, and operational errors; andfor notification to upper layers of the stack of unrecoverable errors.

Layer 3 of stack 205 corresponds to any or all (depending upon theparticular cellular communications protocol) of the network layer, thetransportation layer, the session layer, the presentation layer and theapplication layer of OSI model stack 201. Examples of layer 3 operationsmay include (depending upon the particular cellular communicationsprotocol) call control (CC) management operations, mobility management(MM) operations, subnet convergence protocol (SNDCP) operations, andradio resource (RR) management operations.

Call Control (CC) management operations include operations to managecall routing, call establishment, call maintenance, and call releasefunctions. These operations may be analogous to ISDN call controloperations.

Mobility Management (MM) operations include operations to support themobility of user terminals, such as informing the network of the mobilestation present location and providing user identity authentication andconfidentiality.

Sub Network Dependent Convergence Protocol (SNDCP) operations includeoperations used in a number of different technologies. These operationsmay be used to provide services to the higher layers which may includeconnectionless and connection-oriented modes, compression, multiplexing,and segmentation.

Radio Resource (RR) management operations include operations toestablish, maintain, and release radio resource connections that allow apoint-to-point dialogue between the network and a mobile station.Examples of radio resource management operations include call processingoperations, radio channel control operations, mobile station controloperations, call setup operations, call handoff operations, powercontrol operations, and mobile station lockout operations.

In one embodiment, mobile station 101 is configured to communicate overa cellular communications network as per the Global System for Mobilecommunications (GSM). In other embodiments, mobile station 101 may beconfigured to communicate as per other cellular communications protocolssuch as the code division multiple access (CDMA) protocol, the UniversalMobile Telephone Service (UMTS) wide band CDMA (W-CDMA) protocol, theCDMA2000 protocol, the Time Division—Synchronous Code Division MultipleAccess technology (TD-SCDMA) protocol, the Time Division Multiple Access

(TDMA) protocol, the Integrated Digital Enhanced Network (iDEN)protocol, the Terrestrial Trunked Radio (TETRA) protocol, the GeneralPacket Radio Services (GPRS) protocol, the Enhanced Data Rate for GSMEvolution (EDGE) protocol, the iDEN protocol, and the WiDEN protocol.Operations of each layer of stack 205 may vary with each of thedifferent protocols.

FIG. 3 shows one embodiment of a partitioning of program instructionsfor execution by DSP 127 for performing processor operations. In oneembodiment, the instructions whose partitioning is represented by block301 are stored in a non volatile memory located on integrated circuit103 (e.g. level 1 memory 129 and/or level 2 memory 135) and/or in offchip (level 3) memory 141. In some embodiments, at least some of theinstructions are stored in a compressed format in a non volatile memory,wherein the instructions are decompressed and stored in volatile memoryfor execution by DSP 127. In one embodiment, some instructions arestored in memory 129 and others are stored in memory 135.

In yet another embodiment, at least some of the DSP 127 instructions arestored in memory 151 (in compressed or uncompressed format). MCUprocessor 145 transfers the instructions from memory 151 to DSP 127through either the messaging unit 147 or level 3 memory 141 duringsystem initialization. Upon receipt, DSP 127 validates the authenticityof the memory contents and places the instructions in a memory (level 1memory 129, level 2 memory 135, and/or level 3 memory 141).

In some embodiments, the instructions represented by block 301 areexecuted from a non volatile memory. In other embodiments, theinstructions are executed from volatile memory. The instructionsrepresented by block 301 are implemented using the instruction set forDSP 127.

Block 301 represents instructions for performing modem processoroperations. Modem processor operations are operations performed by aprocessor of a mobile station to facilitate communication as per acellular communications protocol. Layer 3 instructions 305 areinstructions for performing layer 3 processor operations. Layer 3processor operations are processor operations performed by a processorof a mobile station to facilitate layer 3 operations of a cellularcommunications protocol. Examples of Layer 3 processor operations mayinclude (depending upon the particular cellular communications protocol)call control (CC) management processor operations, mobility management(MM) processor operations, subnet convergence protocol (SNDCP) processoroperations, and radio resource (RR) management processor operations.

Layer 2 instructions 307 are instructions for performing layer 2processor operations. Layer 2 processor operations are processoroperations performed by a processor of a mobile station to facilitatelayer 2 operations of a cellular communications protocol. Examples oflayer 2 processor operations may include (depending upon the particularcellular communications protocol) medium access control processoroperations and logical link control processor operations.

Layer 1 instructions 309 are instructions for performing layer 1processor operations. Layer 1 processor operations are operationsperformed by a processor of the mobile station to facilitate layer 1operations of a cellular communications protocol. Examples of layer 1processor operations may include modulation processor operations,demodulation processor operations, interleaving processor operations,deinterleaving processor operations, channel encoding processoroperations, channel decoding processor operations, channel equalizationprocessor operations, synchronization processor operations, automaticgain control processor operations, and automatic frequency controlprocessor operations.

Block 301 also includes instructions 311 for performing audio processingprocessor operations and instructions 315 for performing schedulerprocessor operations. Some of these operations may be unrelated tooperations of a cellular communications protocol.

In one embodiment, instructions for DSP 127 to perform all of the layer3, layer 2, and layer 1 processor operations for mobile station 101 arestored in a memory (129, 135, and/or 141) of mobile station 101. Forexample, instructions for DSP 127 to perform all of the processoroperations for the modem operations described above with respect to aparticular cellular communications protocol (e.g. GSM) are stored in amemory of mobile station 101. In another embodiment, instructions forDSP 127 to perform all layer 2 processor operations and layer 1processor operations and some of the layer 3 processor operations of aparticular cellular communications protocol are stored a memory ofmobile station 101. Accordingly, DSP 127 executes those instructions toperform the processor operations for mobile station 101 to communicateas per the particular cellular communications protocol.

Performing all or substantially all modem processor operations by asingle processor may reduce system cost in that only a single processormay perform modem processor operations and may reduce system complexityin that only one processor instruction set may be utilized for modemfunctionality. Further, using one processor to perform all orsubstantially all of the modem processor operations may reduce oreliminate the amount of messaging between processors of a mobile stationdue to modem operations. Furthermore, such a configuration may savepower in that only one processor needs to be operable during modemoperation. For example, if only a cellular phone function of mobilestation 101 is being utilized, MCU processor 145 may be placed in a lowpower mode in that the modem processor operations needed for thecellular phone function are performed by DSP 127.

Furthermore, a mobile station where all or substantially all of themodem processor operations are performed by DSP 127 may allow forincreased security in that “untrusted” applications running on MCUprocessor 145 would not have access to modem processor operationsperformed by DSP 127. With such an embodiment, a cellular network may beprotected while allowing untrusted applications to be run on MCUprocessor 145. hi some embodiments, untrusted applications may includeapplications which have not been validated to be nonmalicious.

In one embodiment, level 3 memory 141 is shared between MCU processor145 and DSP 127. To protect cellular modem processor instructions fromcorruption by malicious instructions running on MCU processor 145, level3 memory is subdivided into at least two regions. The first region isaccessible only by DSP 127 and is used for holding instructions and datarelated to modem processor operations. This region is inaccessible bythe MCU processor 145, and is therefore secure from maliciousinstructions being executed by it. The second region is shared betweenthe DSP 127 and MCU processor 145. Data and commands are passed betweenthe processors in this region of the level 3 memory 141. Since bothprocessors have access to this region, instructions and data critical tothe cellular modem operations are not stored in this region. In otherembodiments, other memory regions of mobile station 101 could be definedwith other access protections or restrictions depending on securityrequirements.

Referring back to FIG. 1, mobile station 101 includes multiplehierarchal levels of memory with each level having a differentmanufacturing cost and access time. In one embodiment, level 1 memory129 may include volatile and/or non volatile memory having a relativelyfast deterministic access time, but at typically a relatively highercost. In one embodiment, level 1 memory contains instructions and/ordata for performing modem processor operations requiring fastdeterministic access according to a cellular communications protocol.Level 1 cache 131 is utilized to decrease the average access time toinstructions and data stored in level 2 memory 135 and level 3 memory141.

In one embodiment, level 2 memory 135 may include volatile and/or nonvolatile memory having a relatively slower deterministic access time(compared to level 1 memory), but at typically a relatively lower cost.In one embodiment, level 2 memory 135 contains instructions and or datafor performing modem processor operations having determinism and accesstime requirements that are less restrictive than those whoseinstructions and/or data are stored in level 1 memory 129. Level 2 cache137 is utilized to decrease the average access time to level 3 memory141.

In one embodiment, level 3 memory 141 may include volatile and/or nonvolatile memory having relatively the slowest deterministic access time(compared to level 1 and level 2 memory), but at typically the lowestcost. In one embodiment, level 3 memory 141 contains instructions and/ordata for performing modem processor operations having the leastrestrictive determinism and access time requirements.

In other embodiments, mobile stations may have other memoryconfigurations. In some embodiments, some modem operations (e.g. layer 1operations or layer 2 operations) may be performed by hardwareaccelerator 123. In addition, some layer 3 processor operations may beperformed by MCU processor 145. In other embodiments, the memories of amobile station may contain instructions for DSP 127 to perform modemprocessor operations for more than one cellular communications protocol.In other embodiments, other types of processors (e.g. MCU processors)may be utilized to perform the modem processor operations. Furthermore,mobile stations of other embodiments may have other configurations.

In another embodiments, DSP 127 can perform multimedia accelerationfunctions such as decompressing or compressing music or videoinformation. DSP 127 can access multimedia information in shared memory141 written by MCU processor 145. In other embodiments, the DSP 127 canprocess information written to memory 141 by a direct memory access(DMA) (not shown) coupled to MCU bus 150. The processing of multimediainformation may include compressing information received from a camera(not shown) or microphone (e.g. 106 which in some embodiments is alsocoupled to MCU bus 150). The compressed information can be stored by DSP127 into shared memory 141 and accessed by MCU processor 145.

In one embodiment, a cellular mobile station includes communicationinterface circuitry and a cellular modem processor operably coupled tothe communication interface circuitry. The cellular modem processorexecutes instructions from an instruction set. The cellular mobilestation further includes at least one memory coupled to the cellularmodem processor. The at least one memory stores instructions. Theinstructions include instructions that when executed by the cellularmodem processor perform a layer 1 processor operation of a cellularcommunication protocol by the cellular modem processor, instructionsthat when executed by the cellular modem processor perform a layer 2processor operation of the cellular communication protocol by thecellular modem processor, and instructions that when executed by thecellular modem processor perform a layer 3 processor operation of thecellular communication protocol by the cellular modem processor.

In another embodiment, a method of performing cellular modem operationsincludes performing a layer 1 processor operation in accordance with acellular communication protocol by a cellular modem processor,performing a layer 2 processor operation in accordance with the cellularcommunication protocol by the cellular modem processor, and performing alayer 3 processor operation in accordance with the cellularcommunication protocol by the cellular modem processor.

In another embodiment, a method of operating a cellular mobile stationincludes communicating data as per a cellular communications protocol,storing instructions in at least one memory, and performing a layer 1processor operation in accordance with the cellular communicationsprotocol by a cellular modem processor. The method also includesperforming a layer 2 processor operation in accordance with the cellularcommunications protocol by the cellular modem processor and performing alayer 3 processor operation in accordance with the cellularcommunications protocol by the cellular modem processor.

While particular embodiments of the present invention have been shownand described, it will be recognized to those skilled in the art that,based upon the teachings herein, that further changes and modificationsmay be made without departing from this invention and its broaderaspects, and thus, the appended claims are to encompass within theirscope all such changes and modifications as are within the true spiritand scope of this invention.

1-46. (canceled)
 47. An integrated circuit for a cellular mobilestation, the cellular mobile station communicating as per a cellularcommunication protocol, the integrated circuit comprising: a cellularmodem processor, the cellular modem processor to execute instructions toperform a layer 1 processor operations of the cellular communicationprotocol, instructions to perform a layer 2 processor operation of thecellular communication protocol, and instructions to perform a layer 3processor operation of the cellular communication protocol when theintegrated circuit is operational; and a second processor; at least onememory; wherein the second processor performs untrusted processoroperations, wherein untrusted processor operations are not performed bythe cellular modem processor.
 48. The integrated circuit of claim 47wherein processor operations which have not been validated to benonmalicious are not performed by the cellular modem processor.
 49. Theintegrated circuit of claim 48 wherein processor operations which havenot been validated to be nonmalicious are performed by the secondprocessor.
 50. The integrated circuit of claim 47 wherein the secondprocessor does not perform modem processor operations.
 51. Theintegrated circuit of claim 48 wherein the second processor does notperform modem processor operations.
 52. The integrated circuit of claim49 wherein the second processor does not perform modem processoroperations.
 53. The integrated circuit of claim 47 wherein the cellularmodem processor performs all layer 1 processor operations and all layer2 processor operations performed by the integrated circuit.
 54. Theintegrated circuit of claim 48 wherein the cellular modem processorperforms all layer 1 processor operations and all layer 2 processoroperations performed by the integrated circuit.
 55. The integratedcircuit of claim 49 wherein the cellular modem processor performs alllayer 1 processor operations and all layer 2 processor operationsperformed by the integrated circuit.
 56. The integrated circuit of claim50 wherein the cellular modem processor performs all layer 1 processoroperations and all layer 2 processor operations performed by theintegrated circuit.
 57. The integrated circuit of claim 47 whereinprocessor operations which have not been validated to be nonmaliciousare performed by the second processor.
 58. A method of performingprocessor operations comprising: performing a plurality of layer 1processor operations in accordance with a cellular communicationprotocol by a cellular modem processor, performing a layer 2 processoroperation in accordance with the cellular communication protocol by thecellular modem processor; and performing a layer 3 processor operationin accordance with the cellular communication protocol by the cellularmodem processor, performing processor operations by a second processorlocated on the same integrated circuit as the cellular modem processor,wherein the processor operations performed by the second processorinclude an untrusted processor operation, wherein untrusted processoroperations are not performed by the cellular modem processor.
 59. Themethod of claim 58 wherein processor operations which have not beenvalidated to be nonmalicious are not performed by the cellular modemprocessor.
 60. The method of claim 59 wherein the processor operationsperformed by the second processor include a processor operation notvalidated to be nonmalicious.
 61. The method of claim 60 wherein thesecond processor does not perform modem processor operations.
 62. Themethod of claim 59 wherein the second processor does not perform modemprocessor operations.
 63. The method of claim 58 wherein the processoroperations performed by the second processor include a processoroperation not validated to be nonmalicious.
 64. The method of claim 58wherein the cellular modem processor performs all layer 1 processoroperations and all layer 2 processor operations performed by theintegrated circuit.
 65. The method of claim 58 wherein the secondprocessor does not perform modem processor operations.
 66. The method ofclaim 58 wherein the second processor executes application instructions.